Various devices for receiving piles of sheet paper thereon have become known heretofore in the prior art. Such devices serve for making-ready for the sheet-fed press paper sheets which are to be printed. When the board provided with the pile is moved upwardly as required for this purpose, the pile of sheets resting thereon is guided by a pile guide, so that the individual sheets of paper in the pile will be in a correct position for feeding into the press.
U.S. Pat. No. 4,635,924 entitled “Sheet Feeder for a Sheet-Processing Machine”. A sheet feeder for a sheet-processing machine having a device for automatically aligning a lateral position of a stack of sheets from which respective sheets to be individually separated are detectable by a conveyor device for transporting the sheets in a given transport direction and feedable to the sheet-processing machine, includes a stack table for carrying the stack of sheets, the stack table being movable transversely to the given transport direction of the sheets, servomotor means for moving the stack table transversely to the given transport direction in response to respective control signals from an actual sheet-position detection device disposed immediately downstream of the sheet stack as viewed in the given transport direction, the detection device having means for detecting the lateral position of the respective sheet just separated from the stack and already fed to the conveyor device.
U.S. Pat. No. 4,765,606 entitled “Sheet Feeder”. In the context of a sheet feeder comprising a stack carrying table able to be moved by a lifting device and having front and side abutments, precise positioning of the stack is facilitated in as far as the stack carrying table is composed of a supporting table adapted to be connected with a lifting member of the lifting device and of a loading stage supported on the carrying table for free movement in its own plane in substantially all directions within the plane. The sheet feeder furthermore has a clamping device which is able to detachably clamp the stage to the supporting table.
U.S. Pat. No. 4,811,939 entitled “Printing Platform”. A platform for supporting paper and/or cardboard which is to be supplied to a printing press wherein the sheets of paper are stacked on a inner table which is mounted in an outer table for adjustable movement and wherein the outer table is driven vertically so as to lift and automatically feed the paper to a printing press or other machine and wherein the paper can be aligned in a first direction by jogging it against bars fixed to the printing press to align first edges and wherein a sensor senses the lateral position of the upper edges of the sheets of paper and controls an adjusting motor which adjusts the position of the inner table so that the lateral position of the upper sheets being fed to the printing press or at the proper position.
U.S. Pat. No. 4,971,311 entitled “Feeder for Sheet-Feed Printing Machine”. A feeder for use in a sheet-feed printing machine, in which, while a pile board loaded with a paper sheet pile on a pallet is moved upward, paper sheets are fed to the printing unit through a side register lay, comprising a sensor movable along a threaded shaft according to the rotation of the threaded shaft to detect a side edge of the paper sheet pile, which is moved an amount equal to the distance in the cross or lateral direction between a position at which the paper sheet pile is to be positioned when a left-pulling side register lay is used and a position at which the paper sheet pile is to be positioned when a right-pulling side register lay is used, and further comprising a non-interrupting paper replenishing device to insert another paper sheet pile under the paper sheet pile, or detecting means to detect the remaining amount of paper sheets and the top surface of the paper sheet pile.
U.S. Pat. No. 5,615,875 entitled “Device for Receiving Sheet Piles Thereon in a Sheet-Fed Printing Press”. In a sheet-fed printing press, there is provided a device for receiving sheet piles thereon, including a pile table movable up and down, spacers disposed on the pile table, and pile supports of respective sizes corresponding to respective sizes or formats of the sheets disposable on the pile supports, the spacers being distributed over and locally fixed to the pile table so that the respective pile supports of varying sizes rests on a selected number of spacers sufficient for safely supporting the respective pile supports against tilting, the pile supports of respectively smaller size resting on a smaller number of the respective spacers than the pile supports of respectively larger size.
A common problem is that the sheets may not lie flat on the board thereby causing an alignment problem during feeding into the printing press. It has become known from the prior art to interpose spacers between the bottom sheet in the pile and the upper surface of the board to offset sheet curvature problems. These spaces are wedge-shaped, i.e. have the shape of angles in profile, and are displaceably disposed on the board. Problems with such spacers are that several are required correct a curvature that extends between opposite edges of the sheets and such spacers typically do not extend to the central portion of the pile.